Vibrational and structural properties of tetramethyltin under pressure

The vibrational and structural properties of a hydrogen-rich group IVa hydride, Sn(CH₃)₄, have been investigated by combining Raman spectroscopy and synchrotron x-ray diffraction measurements at room temperature and at pressures up to 49.9 GPa. Both techniques allow the obtaining of complementary information on the high-pressure behaviors and yield consistent phase transitions at 0.9 GPa for the liquid to solid and 2.8, 10.4, 20.4, and 32.6 GPa for the solid to solid. The foregoing solid phases are identified to have the orthorhombic, tetragonal, monoclinic crystal structures with space groups of Pmmm for phase I, P4/mmm for phase II, P2/m for phase III, respectively. The phases IV and V coexist with phase III, resulting in complex analysis on the possible structures. These transitions suggest the variation in the inter- and intra-molecular bonding of this compound.